<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>对子标记应用margin负值</title>
<style type="text/css">
.big{
	width:400px;
	height:50px;
	border:2px solid #aaa;
	border-radius:50px;
	background-color:#F36;
	margin:40px auto;
	
}
.small{
	width:80px;
	height:50px;
	background-color:#FFF;
	border:2px solid #CCC;
	margin-top:-30px;           /*将子标记的上部外边距设置为-30px*/
	margin-left:30px;
}   
</style>
</head>
<body>
<div class="big">
	<div class="small"></div>
</div>
</body>
</html>

